Compilare: main.cpp: In function 'int main()': main.cpp:49:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dijkstra.in", "r", stdin); ^ main.cpp:50:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dijkstra.out", "w", stdout); ^ main.cpp:53:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &N, &M); ^ main.cpp: In member function 'void WeightedGraph<T>::readGraph(int, int, bool) [with T = int]': main.cpp:14:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^~~~~